Abstract: An impact detection apparatus (10) includes a device that utilizes multiple sensor elements (11) to determine whether or not a ball lands in or out on a tennis court (12). The sensor positions (13-134) are adjacent to the various boundary lines of the tennis court (12). The sensor elements (11) are layered devices which, when compressed, generate an electrical impulse. The impulse is then analyzed through various signal processing means so that an impact caused a sensor (11) to be compressed may be characterized as being a ball, a footstep, or some other object. In this way, near-simultaneous impacts of a ball and a footstep can be distinguished. If the impact is characterized as a ball that has landed out, a control console (206) will give a visual and/or audible signal so that players, and officials if present, are informed that the ball was out.